/**************************************************************************** * binfmt/binfmt_schedunload.c * * Copyright (C) 2013, 2016 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include "binfmt.h" #if !defined(CONFIG_BINFMT_DISABLE) && defined(CONFIG_SCHED_HAVE_PARENT) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ FAR struct binary_s *g_unloadhead; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: unload_list_add * * Description: * If CONFIG_SCHED_HAVE_PARENT is defined then schedul_unload() will * manage instances of struct binary_s allocated with kmm_malloc. It * will keep the binary data in a link list and when SIGCHLD is received * (meaning that the task has exit'ed, schedul_unload() will find the * data, unload the module, and free the structure. * * This function will add one structure to the linked list * * Input Parameter: * pid - The task ID of the child task * bin - This structure must have been allocated with kmm_malloc() and must * persist until the task unloads * * * Returned Value: * None * ****************************************************************************/ static void unload_list_add(pid_t pid, FAR struct binary_s *bin) { irqstate_t flags; /* Save the PID in the structure so that we recover it later */ bin->pid = pid; /* Disable deliver of any signals while we muck with the list. The graceful * way to do this would be block delivery of SIGCHLD would be with * sigprocmask. Here we do it the quick'n'dirty way by just disabling * interrupts. */ flags = enter_critical_section(); bin->flink = g_unloadhead; g_unloadhead = bin; leave_critical_section(flags); } /**************************************************************************** * Name: unload_list_remove * * Description: * If CONFIG_SCHED_HAVE_PARENT is defined then schedul_unload() will * manage instances of struct binary_s allocated with kmm_malloc. It * will keep the binary data in a link list and when SIGCHLD is received * (meaning that the task has exit'ed, schedul_unload() will find the * data, unload the module, and free the structure. * * This function will remove one structure to the linked list * * Input Parameter: * pid - The task ID of the child task * * Returned Value: * On success, the load structure is returned. NULL is returned on * failure. * ****************************************************************************/ static FAR struct binary_s *unload_list_remove(pid_t pid) { FAR struct binary_s *curr; FAR struct binary_s *prev; /* Note the asymmetry. We do not have to disable interrupts here because * the main thread cannot run while we are in the interrupt handler. Here, * it should be sufficient to disable pre-emption so that no other thread * can run. */ sched_lock(); /* Find the structure in the unload list with the matching PID */ for (prev = NULL, curr = g_unloadhead; curr && (curr->pid != pid); prev = curr, curr = curr->flink); /* Did we find it? It must be there. Hmmm.. we should probably ASSERT if * we do not! */ if (curr) { /* Was there another entry before this one? */ if (prev) { /* Yes.. remove the current entry from after the previous entry */ prev->flink = curr->flink; } else { /* No.. remove the current entry from the head of the list */ g_unloadhead = curr->flink; } /* Nullify the forward link ... superstitious */ curr->flink = NULL; } sched_unlock(); return curr; } /**************************************************************************** * Name: unload_callback * * Description: * If CONFIG_SCHED_HAVE_PARENT is defined, this function may be called to * automatically unload the module when task exits. It assumes that * bin was allocated with kmm_malloc() or friends and will also automatically * free the structure with kmm_free() when the task exists. * * Input Parameter: * pid - The ID of the task that just exited * arg - A reference to the load structure cast to FAR void * * * Returned Value: * None * ****************************************************************************/ static void unload_callback(int signo, siginfo_t *info, void *ucontext) { FAR struct binary_s *bin; int ret; /* Sanity checking */ if (!info || signo != SIGCHLD) { blldbg("ERROR:Bad signal callback: signo=%d info=%p\n", signo, info); return; } /* Get the load information for this pid */ bin = unload_list_remove(info->si_pid); if (!bin) { blldbg("ERROR: Could not find load info for PID=%d\n", info->si_pid); return; } /* Unload the module */ ret = unload_module(bin); if (ret < 0) { blldbg("ERROR: unload_module failed: %d\n", get_errno()); } /* Free the load structure */ kmm_free(bin); } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: schedule_unload * * Description: * If CONFIG_SCHED_HAVE_PARENT is defined, this function may be called by * the parent of the newly created task to automatically unload the * module when the task exits. This assumes that (1) the caller is the * parent of the created task, (2) that bin was allocated with kmm_malloc() * or friends. It will also automatically free the structure with kmm_free() * after unloading the module. * * Input Parameter: * pid - The task ID of the child task * bin - This structure must have been allocated with kmm_malloc() and must * persist until the task unloads * * Returned Value: * This is an end-user function, so it follows the normal convention: * It returns 0 (OK) if the callback was successfully scheduled. On * failure, it returns -1 (ERROR) and sets errno appropriately. * * On failures, the 'bin' structure will not be deallocated and the * module not not be unloaded. * ****************************************************************************/ int schedule_unload(pid_t pid, FAR struct binary_s *bin) { struct sigaction act; struct sigaction oact; sigset_t set; irqstate_t flags; int errorcode; int ret; /* Make sure that SIGCHLD is unmasked */ (void)sigemptyset(&set); (void)sigaddset(&set, SIGCHLD); ret = sigprocmask(SIG_UNBLOCK, &set, NULL); if (ret != OK) { /* The errno value will get trashed by the following debug output */ errorcode = get_errno(); bvdbg("ERROR: sigprocmask failed: %d\n", ret); goto errout; } /* Add the structure to the list. We want to do this *before* connecting * the signal handler. This does, however, make error recovery more * complex if sigaction() fails below because then we have to remove the * unload structure for the list in an unexpected context. */ unload_list_add(pid, bin); /* Register the SIGCHLD handler */ act.sa_sigaction = unload_callback; act.sa_flags = SA_SIGINFO; (void)sigfillset(&act.sa_mask); (void)sigdelset(&act.sa_mask, SIGCHLD); ret = sigaction(SIGCHLD, &act, &oact); if (ret != OK) { /* The errno value will get trashed by the following debug output */ errorcode = get_errno(); bvdbg("ERROR: sigaction failed: %d\n" , ret); /* Emergency removal from the list */ flags = enter_critical_section(); if (unload_list_remove(pid) != bin) { blldbg("ERROR: Failed to remove structure\n"); } leave_critical_section(flags); goto errout; } return OK; errout: set_errno(errorcode); return ERROR; } #endif /* !CONFIG_BINFMT_DISABLE && CONFIG_SCHED_HAVE_PARENT */